Patterning method, method of manufacturing organic field effect transistor, and method of manufacturing flexible printed circuit board

ABSTRACT

In the condition where a nozzle for applying a coating liquid is disposed on the lower side of a substrate and a substrate surface controlled in wettability is faced down, the nozzle and the substrate are moved relative to each other, whereby the coating liquid is applied to a desired region of the substrate, and then the coating liquid is dried, to obtain a pattern included a dried coating layer.

CROSS REFERENCES TO RELATED APPLICATIONS

The present invention contains subject matter related to Japanese PatentApplication JP 2005-083456 filed in the Japanese Patent Office on Mar.23, 2005, the entire contents of which being incorporated herein byreference.

BACKGROUND OF THE INVENTION

The present invention relates to a patterning method, a method ofmanufacturing an organic field effect transistor, and a method ofmanufacturing a flexible printed circuit board.

Field effect transistors (FET) including thin film transistors (ThinFilm Transistor; TFT) used in many electronic apparatuses at presenteach includes, for example, a channel formation region and source/drainregions formed on a silicon semiconductor substrate or a siliconsemiconductor layer, a gate insulation layer of SiO₂ formed on a surfaceof the silicon semiconductor substrate or a surface of the siliconsemiconductor layer, and a gate electrode provided opposite to thechannel formation region through the gate insulation layer.Alternatively, the field effect transistor includes a gate electrodeformed on a support, a gate insulation layer formed on the supportinclusive of the area on the gate electrode, and a channel formationregion and source/drain electrodes which are formed on the gateinsulation layer. In the manufacture of the field effect transistorshaving these structures, very expensive manufacturing apparatuses formanufacturing the semiconductor devices have been used, and there is akeen request for lowering the manufacturing cost.

In view of the above, in recent years, attention has been paid on theresearch and development of an FET which uses an organic semiconductormaterial and which can be manufactured based on a method not using avacuum technology, represented by a printing method, and the performanceof the FET has come to be within an inch of the practical use level.

Conventionally, a patterning method in which a pattern composed of ahydrophilic region and a hydrophobic region is formed on a surface of asubstrate and patterning is conducted by using this as a printing platehas been well known as offset printing method. Inks used in the offsetprinting method are usually high in viscosity, but an example ofpatterning in which low-viscosity liquid materials are used has alsobeen reported.

Besides, Michael L. Chabinyc, et al., “Organic polymeric thin-filmtransistors fabricated by selective dewetting”, APPL. PHYS. Lett81.4260-4262(2002) (hereinafter sometimes referred to as Reference 1)discloses a technology in which a wax is applied to a substrate byprinting, an SAM (Self-Assembled Monolayer) is built up on a substrateregion not covered with the wax, then the wax is removed, and an organicsemiconductor material is built up on the region having been coveredwith the wax (in this region, the SAM is not formed). The organicsemiconductor material is built up by immersing the substrate in asolution of the organic semiconductor material and then pulling up thesubstrate vertically.

Alternatively, technologies in which a coating liquid containing anorganic semiconductor material is applied to a substrate by a diecoating method, a dip coating method, or a spin coating method have alsobeen known.

SUMMARY OF THE INVENTION

However, in the technology disclosed in Reference 1 or theabove-mentioned coating methods according to the related art, thecoating liquid would be present or collected in the region where thecoating liquid should intrinsically not be present, under the influenceof gravity, so that in some cases it is difficult to obtain the desiredpattern. Besides, in the dip coating method, there arises the problemthat both sides of the substrate would be wetted with the coatingliquid, or the problem that the coating growth speed would be low. Thespin coating method involves the problem that most part of the coatingliquid would be wasted.

Thus, there is a need to provide a patterning method capable ofassuredly solving the problem involved in the coating methods accordingto the related art, i.e., the problem that the coating liquid would bepresent or collected in the regions where the coating liquid shouldintrinsically not be present, under the influence of gravity, with theresult of difficulties in obtaining the desired pattern, as well as amethod of manufacturing an organic field effect transistor by applyingthe pattering method, and a method of manufacturing a flexible printedcircuit board by applying the patterning method.

In order to fulfill the above-mentioned need, according to an embodimentof the present invention, there is provided a patterning method whereina nozzle for applying a coating liquid and a substrate are movedrelative to each other in the condition where the nozzle is disposed onthe lower side of the substrate and a substrate surface controlled inwettability is faced down, so as thereby to apply the coating liquid toa desired region of the substrate, and thereafter the coating liquid isdried so as thereby to obtain a dried coating layer.

In the patterning method of the present invention, preferably, but notlimitatively, the substrate is provided with a recess-projectionstructure having a recessed portion as the desired region and aprojected portion so as thereby to control the wettability of thesurface of the substrate, and the coating liquid is applied to therecessed portion.

In addition, in the patterning method of the present invention,preferably, the relationship of θ<θ′ is satisfied, where θ is thecontact angle between the desired region of the substrate and thecoating liquid, and θ′ is the contact angle between the other region ofthe substrate than the desired region and the coating liquid.Specifically, in the case where the desired region of the substrate isset to be lyophilic, the other region of the substrate than the desiredregion is desirably set to be lyophobic or liquid-repellent, or, in thecase where the desired region of the substrate is set to be lyophobic,the other region of the substrate than the desired region is desirablyset to be liquid-repellent. Here, a lyophilic surface means that thecontact angle between the surface and the coating liquid is less than 90degrees, whereas a lyophobic surface means that the contact anglebetween the surface and the coating liquid is not less than 90 degreesand less than 110 degrees, and a liquid-repellent surface means that thecontact angle between the surface and the coating liquid is not lessthan 110 degrees. In some cases, the relationship of θ>θ′ may besatisfied, though depending on the properties of the substrate and thecoating liquid which are used.

While the desired pattern is formed on the substrate in the patteringmethod of the present invention, in some cases, a method may be adoptedin which a pattern composed of the dried coating layer is formed and,thereafter, the pattern is transferred onto a second substrate tothereby provide the second substrate with the desired pattern. Examplesof specific methods for transferring the pattern onto the secondsubstrate include a method in which, for example, poly-3-hexylthiophene(P3HP) as an ink is mounted on a projected portion of a stamp having arecess-projection structure (a stamp formed from a fluoro-resin, a stampproduced from a substrate surface-treated with a fluoro-resin, or astamp treated with 10 mmol of OTS), thereafter the P3HP mounted on theprojected surface of the stamp is transferred onto a wholly flat PDMS(silicon rubber), and then the P3HP transferred onto the PDMS istransferred onto the desired second substrate.

According to another embodiment of the present invention, there isprovided a method of manufacturing an organic field effect transistor,which is a method of manufacturing a so-calledbottom-gate/bottom-contact type organic field effect transistor,including the steps of:

(A) forming a gate electrode on a substrate,

(B) thereafter forming a gate insulation layer over the entire surface,

(C) then forming source/drain electrodes on the gate insulation layer,and

(D) thereafter forming a channel formation region in a portion, betweenthe source/drain electrode and the source/drain electrode, of the gateinsulation layer, wherein

in the step (D), a nozzle for applying an organic semiconductor materialcoating liquid and the substrate are moved relative to each other in thecondition where the nozzle is disposed on the lower side of thesubstrate, and the substrate surface provided thereon with the gateinsulation layer and the source/drain electrodes and controlled inwettability is faced down, so as thereby to apply the organicsemiconductor material coating liquid to the portion, between thesource/drain electrode and the source/drain electrode, of the gateinsulation layer, and thereafter the organic semiconductor materialcoating liquid is dried so as thereby to obtain a channel formationregion included the organic semiconductor material.

Incidentally, the bottom-gate/bottom-contact type organic field effecttransistor thus obtained includes:

(a) a gate electrode formed on a substrate,

(b) a gate insulation layer formed on the gate electrode,

(c) source/drain electrodes formed on the gate insulation layer, and

(d) a channel formation region formed on a portion, between thesource/drain electrodes, of the gate insulation layer.

In addition, according to a further embodiment of the present invention,there is provided a method of manufacturing an organic field effecttransistor, which is a method of manufacturing a so-calledbottom-gate/top-contact type organic field effect transistor, includingthe steps of:

(A) forming a gate electrode on a substrate,

(B) thereafter forming a gate insulation layer on the entire surface,

(C) then forming a channel formation region and channel formation regionextension portions on the gate insulation layer, and

(D) thereafter forming source/drain electrodes on the channel formationregion extension portions, wherein

in the step (C), a nozzle for applying an organic semiconductor materialcoating liquid and the substrate are moved relative to each other in thecondition where the nozzle is disposed on the lower side of thesubstrate and the substrate surface provided thereon with the gateinsulation layer and controlled in wettability is faced down, so asthereby to apply the organic semiconductor material coating liquid tothe gate insulation layer, and thereafter the organic semiconductormaterial coating liquid is dried so as thereby to obtain the channelformation region and the channel formation region extension portionswhich are included an organic semiconductor material.

Incidentally, the bottom-gate/top-contact type organic field effecttransistor thus obtained includes:

(a) a gate electrode formed on a substrate,

(b) a gate insulation layer formed on the gate electrode,

(c) a channel formation region and channel formation region extensionportions which are formed on the gate insulation layer, and

(d) source/drain electrodes formed on the channel formation regionextension portions.

Further, according to yet another embodiment of the present invention,there is provided a method of manufacturing an organic field effecttransistor, which is a method of manufacturing a so-calledtop-gate/bottom-contact type organic field effect transistor, includingthe steps of:

(A) forming source/drain electrodes on a substrate,

(B) thereafter forming a channel formation region in a portion, betweenthe source/drain electrode and the source/drain electrode, of thesubstrate,

(C) then forming a gate insulation layer on the entire surface, and

(D) thereafter forming a gate electrode on the gate insulation layer,wherein

in the step (B), a nozzle for applying an organic semiconductor materialcoating liquid and the substrate are moved relative to each other in thecondition where the substrate surface provided thereon with thesource/drain electrodes and controlled in wettability is faced down, soas thereby to apply the organic semiconductor material coating liquid toa portion, between the source/drain electrode and the source/drainelectrode, of the substrate, and thereafter the organic semiconductormaterial coating liquid is dried so as thereby to obtain the channelformation region formed of an organic semiconductor material.

Incidentally, the top-gate/bottom-contact type organic field effecttransistor thus obtained includes:

(a) source/drain electrodes formed on a substrate,

(b) a channel formation region formed on a portion, between thesource/drain electrodes, of the substrate,

(c) a gate insulation layer formed on the channel formation region, and

(d) a gate electrode formed on the gate insulation layer.

Besides, according to a yet further embodiment of the present invention,there is provided a method of manufacturing an organic field effecttransistor, which is a method of manufacturing a so-calledtop-gate/top-contact type organic field effect transistor, including thesteps of:

(A) forming a channel formation region and channel formation regionextension portions on a substrate,

(B) thereafter forming source/drain electrodes on the channel formationregion extension portions,

(C) then forming a gate insulation layer over the entire surface, and

(D) thereafter forming a gate electrode on the gate insulation layer,wherein

in the step (A), a nozzle for applying an organic semiconductor materialcoating liquid and the substrate are moved relative to each other in thecondition where the nozzle is disposed on the lower side of thesubstrate and a substrate surface controlled in wettability is faceddown, so as thereby to apply the organic semiconductor material coatingliquid to the substrate, and thereafter the organic semiconductormaterial coating liquid is dried so as thereby to obtain the channelformation region and the channel formation region extension portionswhich are formed of an organic semiconductor material.

Incidentally, the top-gate/top-contact type organic field effecttransistor thus obtained includes:

(a) a channel formation region and channel formation region extensionportions which are formed on a substrate,

(b) source/drain electrodes formed on the channel formation regionextension portions,

(c) a gate insulation layer formed on the source/drain electrodes andthe channel formation region, and

(d) a gate electrode formed on the gate insulation layer.

According to still another embodiment of the present invention, there isprovided a method of manufacturing a flexible printed circuit board,wherein a nozzle for applying a conductive material coating liquid and asubstrate are moved relative to each other in the condition where thenozzle is disposed on the lower side of the substrate and a substratesurface controlled in wettability is faced down, so as thereby to applythe conductive material coating liquid to the substrate, and thereafterthe conductive material coating liquid is dried so as thereby to obtaina circuit pattern composed of a conductive material coating layer.

As a coating apparatus including a nozzle for use in the patterningmethod, the method of manufacturing an organic field effect transistoror the method of manufacturing a flexible printed circuit boardaccording to the present invention (hereinafter, these methods will insome cases be generically referred to simply as the present invention),there may be mentioned the so-called capillary coater. The relativemovement between the nozzle and the substrate may be achieved by movingthe substrate while the nozzle is fixed, or by moving the nozzle whilethe substrate is fixed, or by moving both the nozzle and the substrate.

As the coating liquid in the patterning method of the present invention,there may be mentioned coating liquids which are each prepared bydissolving an organic semiconductor material in a solvent. Specificexamples of the combination of [organic semiconductor material, solvent]include [poly-3-hexylthiophene, toluene], [poly-3-hexylthiophene,chloroform], [poly-3-hexylthiophene, xylene], [poly-3-hexylthiophene,tetrahydrofuran (THF)], and [poly-3-hexylthiophene, chlorobenzene].

Alternatively, as the coating liquid in the patterning method of thepresent invention, there may be mentioned coating liquids which are eachprepared by dissolving a conductive material in a solvent. Specificexamples of the combination of [conductive material, solvent] include[poly(3,4-ethylenedioxythiophene)/polystyrenesulfonic acid [PEDOT/PSS],water], [PEDOT/PSS, mixed liquid of isopropyl alcohol and water],[PEDOT/PSS, mixed liquid of water and surfactant], [PEDOT/PSS, mixedliquid of water and ethylene glycol], [silver nano-particles, ethylacetate], [silver nano-particles, water], [silver nano-particles,toluene], [gold nano-particles, toluene], [gold nano-particles,chloroform], and [gold nano-particles, hexane].

Or, as the coating liquid in the patterning method of the presentinvention, there may be mentioned coating liquids which are eachprepared by dissolving an organic EL material in a solvent. Specificexamples of the combination of [organic EL material, solvent] include[MEH-PPV, chlorobenzene].

In addition, as the organic semiconductor material coating liquid in themethods of manufacturing an organic field effect transistor according tothe another embodiment, the further embodiment, the yet anotherembodiment and the yet further embodiment of the present invention(hereinafter, these methods will in some cases be generically referredto simply as the method of manufacturing an organic field effecttransistor according to the present invention), there may be mentionedcoating liquids which are each prepared by dissolving an organicsemiconductor material in a solvent. Specific examples of thecombination of [organic semiconductor material, solvent] include thesame combinations as the above-mentioned combinations of [organicsemiconductor material, solvent] in the patterning method of the presentinvention.

Further, as the conductive material coating liquid in the method ofmanufacturing a flexible printed circuit board according to the presentinvention, there may be mentioned coating liquids which are eachprepared by dissolving a conductive material in a solvent. Specificexamples of the combination of [conductive material, solvent] includethe same combinations as the above-mentioned combinations of [conductivematerial, solvent] in the pattering method of the present invention.

In order to obtain the substrate surface controlled in wettability inthe pattering method of the present invention or the method ofmanufacturing a flexible circuit board according to the presentinvention, it suffices, for example, to treat the surface of the desiredregion of the substrate or to treat the surface of the other region ofthe substrate than the desired region so that the relationship of θ<θ′is satisfied, where θ is the contact angle between the desired region ofthe substrate and the coating liquid, and θ′ is the contact anglebetween the other region of the substrate than the desired region andthe coating liquid. As such a treatment, for example, a method ofcovering the other region of the substrate than the desired region witha material showing a large angle of contact with the coating liquid.Examples of such a material include octadecyltrimethoxysilane (OTS) andhexamethylenedisilazane (HMDS). Another method which can be adopted is amethod wherein the surface of the desired region of the substrate ismade to be lyophilic by treatment with aminotrichlorosilane, and theother region of the substrate than the desired region is made to beliquid-repellent by treatment with perfluorooctyltrichlorosilane.Further methods which can be adopted include a method wherein thesurface of the substrate is made to be lyophilic by an oxygen plasmatreatment, and a method wherein toner particles are transferred andfixed onto the surface of the substrate by use of a dry indirectelectrostatic copying machine so as to form a liquid-repellent region orlyophobic region composed of the toner particles on the surface of thesubstrate.

In addition, in order to obtain the substrate surface provided thereonwith the gate insulation layer and the source/drain electrodes andcontrolled in wettability in the method of manufacturing an organicfield effect transistor according to the another embodiment of thepresent invention, for example, a method may be adopted in which theother region than the region to which the organic semiconductor materialcoating liquid is to be applied, of the surface provided thereon withthe gate insulation layer and the source/drain electrodes, is coveredwith a material showing a large angle of contact with the coatingliquid. Besides, in order to obtain the substrate surface providedthereon with the gate insulation layer and controlled in wettability inthe method of manufacturing an organic field effect transistor accordingto the further embodiment of the present invention, for example, amethod may be adopted in which the other region than the region to whichthe organic semiconductor material coating liquid is to be applied, ofthe surface provided thereon with the gate insulation layer, is coveredwith a material showing a large angle of contact with the coatingliquid. Further, in order to obtain the substrate surface providedthereon with the source/drain electrodes and controlled in wettabilityin the method of manufacturing an organic field effect transistoraccording to the yet another embodiment of the present invention, forexample, a method may be adopted in which the other region than theregion to which the organic semiconductor material coating liquid is tobe applied, of the surface provided thereon with the source/drainelectrodes, is covered with a material showing a large angle of contactwith the coating liquid. In addition, in order to obtain the substratesurface controlled in wettability in the method of manufacturing anorganic field effect transistor according to the yet further embodimentof the present invention, for example, a method may be adopted in whichthe other region than the region to which the organic semiconductormaterial coating liquid is to be applied, of the relevant substratesurface, is covered with a material showing a large angle of contactwith the coating liquid. Here, examples of the relevant material includeoctadecyltrimethoxysilane (OTS), and perfluorooctyltrichlorosilane.

In the method of manufacturing an organic field effect transistoraccording to the present invention, examples of the materialconstituting the gate insulation layer include not only inorganicinsulating materials such as silicon oxide based materials, siliconnitride (SiN_(Y)), Al₂O₃, and metal oxide highly dielectric insulatingmaterials but also organic insulating materials such as polymethylmethacrylate (PMMA), polyvinyl phenol (PVP), polyethylene terephthalate(PET), polyoxymethylene (POM), polyvinyl chloride, polyvinylidenefluoride, polysulfone, polycarbonate (PC), and polyimides, andcombinations of these materials. Incidentally, examples of the siliconoxide based materials include silicon dioxide (SiO₂), BPSG, PSG, BSG,AsSG, PbSG, silicon oxynitride (SiON), SOG (Spin On Glass), andlow-dielectric-constant SiO_(X) based materials (e.g., polyaryl ethers,cycloperfluorocarbon polymers, and benzocyclobutene, cyclicfluoro-resins, polytetrafluoroethylene, aryl ether fluorides, polyimidefluorides, amorphous carbon, organic SOG).

Examples of the method for forming the gate insulation layer includevarious printing methods such as screen printing method, ink jetprinting method, offset printing method, gravure printing method, etc.;various coating methods such as air doctor coater method, blade coatermethod, rod coater method, knife coater method, squeeze coater method,reverse roll coater method, transfer roll coater method, gravure coatermethod, kiss coater method, cast coater method, spray coater method,slit orifice coater method, calender coater method, etc.; various CVDmethods; dip method; casting method; spin coat method; spray method; andvarious PVD methods. Here, examples of the PVD methods include (a)various vacuum evaporation methods such as electron beam heating method,resistance heating method, flash evaporation method, etc., (b) plasmavapor deposition methods, (c) various sputtering methods such astwo-pole sputtering method, DC (direct current) sputtering method, DCmagnetron sputtering method, RF sputtering method, magnetron sputteringmethod, ion beam sputtering method, bias sputtering method, etc., and(d) various ion plating methods such as DC method, RF method,multi-cathode method, activation reaction method, electric field vapordeposition method, high-frequency ion plating method, reactive ionplating method, etc.

Alternatively, the gate insulation layer can be formed by oxidizing ornitriding the surface of the gate electrode, or by forming an oxide filmor nitride film at the surface of the gate electrode. Examples of themethod for oxidizing the surface of the gate electrode, though dependingon the material constituting the gate electrode, include a thermaloxidation method, an oxidizing method using an O₂ plasma, and an anodicoxidation method. Examples of the method for nitriding the surface ofthe gate electrode, though depending on the material constituting thegate electrode, include a nitriding method using an N₂ plasma. Or,alternatively, in the case where the gate electrode is constituted ofgold (Au), for example, the gate insulation layer can be formed at thesurface of the gate electrode by self-organizingly covering the gateelectrode surface with insulating molecules having a functional groupcapable of forming a chemical bond with the gate electrode, such as astraight chain hydrocarbon modified with a mercapto group at one endthereof, while using such a method as dipping method.

Or, the gate insulation layer can be formed by application of thepatterning method according to the present invention.

Further, in the organic field effect transistor according to the presentinvention, examples of the material constituting the gate electrode, thesource/drain electrodes and various wirings include metals such asplatinum (Pt), gold (Au), palladium (Pd), chromium (Cr), nickel (Ni),molybdenum (Mo), niobium (Nb), neodymium (Nd), aluminum (Al), silver(Ag), tantalum (Ta), tungsten (W), copper (Cu), rubidium (Rb), rhodium(Rh), titanium (Ti), indium (In), tin (Sn), etc., alloys containing anyof these metallic elements, conductive particles of these metals,conductive particles of alloys containing any of these metals,polysilicon, amorphous silicon, tin oxide, indium oxide, indium tinoxide (ITO), and laminate structures of layers containing any of theseelements.

Examples of the method for forming the source/drain electrodes and thegate electrode, though depending on the materials constituting theseelectrodes, include spin coating method; the above-mentioned variousprinting methods using any of various conductive pastes and variousconductive polymer solutions; the above-mentioned various coatingmethods; lift-off method; shadow mask method; plating methods such aselectroplating method, electroless plating method, and combination ofthese; spraying method; the above-mentioned various PVD methods; andvarious CVD methods including MOCVD method; which may further becombined with patterning technology, as required.

Furthermore, examples of the materials for forming the gate electrodeand the source/drain electrodes include such organic materials asPEDOT/PSS. In this case, the gate electrode can be formed further byapplication of the pattering method according to the present invention.

In the patterning method according to the present invention or themethod of manufacturing an organic field effect transistor according tothe present invention, examples of the substrate or the second substrateinclude various glass substrates, various glass substrates provided withan insulation layer on the surface thereof, quartz substrate, quartzsubstrate provided with an insulation layer on the surface thereof, andsilicon substrate provided with an insulation layer on the surfacethereof. Further examples of the substrate or the second substrate inthe pattering method according to the present invention or the method ofmanufacturing an organic field effect transistor according to thepresent invention include plastic films, plastic sheets and plasticsubstrates formed of a polymer material such as polyether sulfone (PES),polyimides, polycarbonate (PC), polyethylene terephthalate (PET),polymethyl methacrylate (PMMA), polyvinyl alcohol (PVA), and polyvinylphenol (PVP); when the substrate or second substrate constituted of sucha flexible polymer material is used, it is possible to incorporate orintegrate the organic field effect transistor into or with, for example,displays or electronic apparatus having a curved surface. Yet furtherexamples of the substrate or the second substrate include conductivesubstrates (substrates formed of a metal, such as gold, or highlyoriented graphite). Besides, in the method of manufacturing an organicfield effect transistor according to the present invention, the organicfield effect transistor may in some cases be provided on a supportmember, depending on the configuration or structure of the organic fieldeffect transistor; in such a case, the support member may be composed ofany of the above-mentioned materials. In addition, examples of thesubstrate or the second substrate in the method of manufacturing aflexible printed circuit board according to the present inventioninclude flexible plastic films composed of polymer materials such aspolyether sulfone (PES), polyimides, polycarbonate (PC), polyethyleneterephthalate (PET), polymethyl methacrylate (PMMA), polyvinyl alcohol(PVA), and polyvinyl phenol (PVP).

In the case where the organic field effect transistor obtained by themethod of manufacturing an organic field effect transistor according tothe present invention is applied to or used in displays or variouselectronic apparatuses, a multiplicity of the organic field effecttransistors may be integrated on a substrate to obtain a monolithicintegrated circuit, or the respective organic field effect transistorsmay be cut off individually to be used as discrete component parts. Inaddition, the organic field effect transistor may be potted with aresin.

In the present invention, the nozzle for applying a coating liquid orthe like and a substrate or the like are moved relative to each other inthe condition where the nozzle is disposed on the lower side of thesubstrate or the like and the surface of the substrate or the likecontrolled in wettability is faced down, so as thereby to apply thecoating liquid or the like to a desired region of the substrate or thelike. Therefore, it is possible to assuredly solve the problem involvedin the conventional coating method, i.e., the problem that the coatingliquid or the like would be present or collected on the region where thecoating liquid should intrinsically not be present, under the influenceof gravity. Then, it is possible to apply the coating liquid or the liketo a large-area substrate or the like comparatively easily and with highaccuracy, and wasting of the coating liquid or the like can be avoided.Further, it is possible to use a low-viscosity coating liquid, and tocontrive enhancement of the accuracy in forming a pattern or the like.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are diagrams showing the outline of a capillary coater,and schematically illustrate the condition where a coating liquid isbeing applied to a substrate by use of the capillary coater;

FIGS. 2A and 2B are diagrams showing the outline of the capillarycoater, and schematically illustrate the condition where the coatingliquid is being applied to the substrate by use of the capillary coater,subsequent to the instance of FIG. 1B;

FIGS. 3A and 3B are diagrams showing the outline of the capillarycoater, and schematically illustrate the condition where the coatingliquid is being applied to the substrate by use of the capillary coater,subsequent to the instance of FIG. 2B;

FIGS. 4A to 4D are schematic partly sectional diagrams of a substrate orthe like for illustrating a patterning method in Embodiment 1 and amethod of manufacturing an organic field effect transistor in Embodiment1;

FIGS. 5A to 5D are schematic partly sectional diagrams of the substrateor the like for illustrating the patterning method in Embodiment 1 andthe method of manufacturing an organic field effect transistor inEmbodiment 1, subsequent to the instance of FIG. 4D;

FIGS. 6A to 6D are schematic partly sectional diagrams of a substrate orthe like for illustrating a patterning method in Embodiment 2 and amethod of manufacturing an organic field effect transistor in Embodiment2;

FIGS. 7A to 7D are schematic partly sectional diagrams of a substrate orthe like for illustrating a pattering method in Embodiment 3 and amethod of manufacturing an organic field effect transistor in Embodiment3;

FIGS. 8A and 8B are schematic partly sectional diagrams of the substrateor the like for illustrating the patterning method in Embodiment 3 andthe method of manufacturing an organic field effect transistor inEmbodiment 3, subsequent to the instance of FIG. 7D;

FIGS. 9A to 9D are schematic partly sectional diagrams of a substrate orthe like for illustrating a patterning method in Embodiment 4 and amethod of manufacturing an organic field effect in Embodiment 4;

FIGS. 10A and 10B are schematic partly sectional diagrams of thesubstrate or the like for illustrating the patterning method inEmbodiment 4 and the method of manufacturing an organic field effect inEmbodiment 4, subsequent to the instance of FIG. 9D;

FIGS. 11A and 11B are schematic partly sectional diagrams of a substrateor the like for illustrating a patterning method in Embodiment 5; and

FIGS. 12A to 12D are schematic partly sectional diagrams of a substrateor the like for illustrating a patterning method in Embodiment 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now, the present invention will be described below based on embodimentsthereof, referring to the drawings. First, the outline of a capillarycoater suited for carrying out an embodiment of the present inventionwill be described referring to FIGS. 1A and 1B, FIGS. 2A and 2B, andFIGS. 3A and 3B.

As a conceptual diagram is shown in FIG. 1A, the capillary coater 10includes a tank 11 for reserving a coating liquid 20, and a nozzle 12disposed inside the tank 11 and moved up and down by a lift (not shown).A tip end portion of the nozzle 12 is provided with a slit; as shown inthe conceptual diagram in FIG. 1B, when the nozzle 12 is located at anelevated position by operating the lift (not shown), the coating liquid20 protrudes from the slit in the tip end portion of the nozzle 12 bycapillarity. Incidentally, the slit extends in the directionperpendicular to the paper surface of the drawing.

In the condition as a conceptual diagram is shown in FIG. 2A, asubstrate 30 is moved from the right side toward the left side in thedrawing by a moving device (not shown), whereon the coating liquid 20protruding from the slit in the tip end portion of the nozzle 12 bycapillarity is applied to the substrate 30, as a conceptual diagram isshown in FIG. 2B. The distance (gap) between the tip end portion of thenozzle 12 and the substrate 30 is kept at 0.2 mm, for example, and themoving velocity of the substrate is set at 0.7 m/min. Incidentally, thecoating liquid applied to the substrate 30 is indicated as a coatingliquid 21. Simultaneously, the coating liquid 20 in the tank 11 iscontinuedly supplied to the slit in the tip end portion of the nozzle 12by capillarity. When the application of the coating liquid 20 to thesubstrate 30 is completed (see a conceptual diagram shown in FIG. 3A),the nozzle 12 is located at a lowered position by an operation of thelift (not shown) (see a conceptual diagram shown in FIG. 3B). In thismanner, the application of the coating liquid to a desired region of thesingle substrate is completed.

Embodiment 1

Embodiment 1 relates to the pattering method according to the oneembodiment of the present invention and the method of manufacturing anorganic field effect transistor according to the another embodiment ofthe present invention. Now, referring to FIGS. 4A to 4D and FIGS. 5A to5D which are schematic partly end elevation diagrams of a substrate orthe like, the pattering method according to Embodiment 1 and the methodof manufacturing an organic field effect transistor according toEmbodiment 1 will be described below. Incidentally, in Embodiment 1, thepattering method is applied to the formation of a gate electrode of theorganic field effect transistor and to the formation of a channelformation region.

Besides, in Embodiment 1 or in Embodiments 2 to 4 which will bedescribed later, the channel formation region 38 is formed on the basisof a toluene solution of poly-3-hyxylthiophene (P3HP), and the gateelectrode 34 is formed on the basis of an aqueous solution of PEDOT/PSS.Here, the contact angles θ and θ′ of these solutions are shown in Table1 below. In Table 1, “OTS” means octadecyltrimethoxysilane, and theconcentration thereof is 1 mmol. TABLE 1 Liquid Solid Contact angleToluene solution of P3HP SiO₂ θ = ca. 30° or below Toluene solution ofP3HP Au θ = ca. 30° or below Toluene solution of P3HP OTS θ′ = ca. 40°Aqueous solution of PEDOT/PSS SiO₂ θ = ca. 34° Aqueous solution ofPEDOT/PSS OTS θ′ = ca. 110°

[Step 100]

First, the gate electrode 34 is formed on the substrate 30 prepared byforming an insulation film 32 of SiO₂ on a surface of the glasssubstrate 31. Specifically, a coating layer 33 composed ofoctadecyltrimethoxysilane (OTS) from which the portion to be providedwith the gate electrode 34 has been removed is formed on the insulationfilm 32 by a PDMS stamp method, for example. This condition is shown inthe schematic partly end elevation diagram of FIG. 4A.

Next, the patterning method according to the present invention isapplied. Specifically, in the condition where a nozzle 12 for applyingan aqueous PEDOT/PSS solution as the coating liquid is disposed on thelower side of the substrate (see FIGS. 1A, 1B, and 2A) and the surfaceof the substrate 30 controlled in wettability (namely, the surface ofthe substrate 30 provided with the coating layer 33) is faced down, thenozzle 12 and the substrate 30 are moved relative to each other (seeFIGS. 2A, 2B, and 3A), whereby the coating liquid 34A is applied to thedesired region (specifically, the region of the insulation film 32 wherethe gate electrode 34 is to be formed) of the substrate 30. Thiscondition is shown in the schematic partly end elevation of FIG. 4B.Thereafter, the coating liquid 34A is dried, whereby a pattern composedof the dried coating layer, i.e., the gate electrode 34 formed ofPEDOT/PSS can be obtained (see the schematic partly end elevationdiagram of FIG. 4C).

[Step 110]

Next, a gate insulation layer 35 is formed over the entire surface.Specifically, the gate insulation layer 35 of SiO₂ is formed on theentire surface (specifically, on the gate electrode 34 and the coatinglayer 33) based on a sputtering method (see the schematic partly endelevation diagram of FIG. 4D). At the time of forming the gateinsulation layer 35, a part of the gate electrode 34 is covered with ahard mask, whereby a take-out portion (not shown) of the gate electrode34 can be formed without any photolithographic process.

[Step 120]

Thereafter, source/drain electrodes 36 are formed on the gate insulationlayer 35. Specifically, a titanium (Ti) layer (not shown) as a closecontact layer and a gold (Au) layer as the source/drain electrodes 36are sequentially formed on the basis of a vacuum evaporation method. Inthis manner, the structure as shown in FIG. 5A can be obtained. At thetime of forming the close contact layer and the source/drain electrodes36, the region where the channel formation region 38 is to be formed iscovered with a hard mask, whereby the source/drain electrodes 36 can beformed without any photolithographic process.

[Step 130]

Next, the channel formation region 38 is formed on the portion, betweenthe source/drain electrode 36 and the source/drain electrode 36, of thegate insulation layer 35.

For this purpose, first, a coating layer 37 composed ofoctadecyltrimethoxysilane (OTS) from which the portion where the channelformation region 38 is to be formed has been removed is formed by a PDMSstamp method, for example. This condition is shown in the schematicpartly end elevation diagram of FIG. 5B.

Then, in the condition where the nozzle 12 for applying an organicsemiconductor material coating liquid composed of a toluene solution ofP3HP (5 g/l) is disposed on the lower side of the substrate 30 (seeFIGS. 1A, 1B, and 2A) and substrate surface provided thereon with thegate insulation layer 35 and the source/drain electrode 36 andcontrolled in wettability (namely, the surface of the substrate providedthereon with the coating layer 37) is faced down, the nozzle 12 and thesubstrate 30 are moved relative to each other (see FIGS. 2A, 2B, and3A), whereby the organic semiconductor material coating liquid 38A isapplied to the portion, between the source/drain electrode 36 and thesource/drain electrode 36, of the gate insulation layer 35. Thiscondition is shown in the schematic partly end elevation diagram of FIG.5C. Thereafter, the organic semiconductor material coating liquid 38A isdried, whereby the channel formation region 38 composed of P3HP which isan organic semiconductor material can be obtained (see the schematicpartly end elevation diagram of FIG. 5D).

Or, in other words, in the condition where the nozzle 12 for applyingthe toluene solution of P3HP as the coating liquid is disposed on thelower side of the substrate 30 (see FIGS. 1A, 1B, and 2A) and thesurface of the substrate 30 controlled in wettability (namely, thesurface of the substrate 30 provided thereon with the coating layer 37)is faced down, the nozzle 12 and the substrate 30 are moved relative toeach other (see FIGS. 2A, 2B, and 3A), whereby the coating liquid 38A isapplied to the desired region (specifically, the region of the gateinsulation layer 35 where the channel formation region 38 is to beformed) of the substrate 30 (see the schematic partly end elevationdiagram of FIG. 5C). Thereafter, the coating liquid 38A is dried,whereby a pattern composed of the dried coating layer, i.e., the channelformation region 38 composed of P3HP can be obtained (see the schematicpartly end elevation diagram of FIG. 5D).

[Step 140]

Finally, an insulation layer (not shown) as a passivation film is formedon the entire surface, the insulation layer on the upper side of thesource/drain electrodes 36 is provided with openings, a wiring materiallayer is formed on the entire surface inclusive of the inside of theopenings, and thereafter the wiring material layer is patterned, wherebya bottom-gate/bottom-contact type organic field effect transistor inwhich wirings (not shown) connected to the source/drain electrodes 36are formed on the insulation layer can be obtained.

Specifically, the bottom-gate/bottom-contact type organic field effecttransistor includes:

(a) the gate electrode 34 formed on the substrate 30,

(b) the gate insulation layer 35 formed on the gate electrode 34,

(c) the source/drain electrodes 36 formed on the gate insulation layer35, and

(d) the channel formation region 38 formed on the portion, between thesource/drain electrodes 36, of the gate insulation layer 35.

Embodiment 2

Embodiment 2 relates to the patterning method according to the oneembodiment of the present invention and the method of manufacturing anorganic field effect transistor according to the further embodiment ofthe present invention. Now, the patterning method in Embodiment 2 andthe method of manufacturing an organic field effect transistor inEmbodiment 2 will be described below referring to FIGS. 6A to 6D whichare schematic partly end elevation diagrams of a substrate or the like.In Embodiment 2, also, the patterning method is applied to the formationof a gate transistor and the formation of a channel formation region, inthe organic field effect transistor.

[Step 200]

First, the same step as [Step 100] in Embodiment 1 is carried out toform the gate electrode 34 on the substrate 30, and thereafter the samestep as [Step 110] in Embodiment 1 is carried out to form a gateinsulation layer 35 on the entire surface.

[Step 210]

Next, a channel formation region 38 and channel formation regionextension portions 39 are formed on the gate insulation layer 35.Specifically, the same step as [Step 130] in Embodiment 1 is carriedout. To be more specific, a coating layer 37 composed ofoctadecyltrimethoxysilane (OTS) from which the portions where thechannel formation region 38 and the channel formation region extensionportions 39 are to be formed have been removed is formed by a PDMS stampmethod, for example. This condition is shown in the schematic partly endelevation diagram of FIG. 6A.

Then, in the condition where a nozzle 12 for applying an organicsemiconductor material coating liquid consisting of a toluene solutionof P3HP (5 g/l) is disposed on the lower side of the substrate 30 (seeFIGS. 1A, 1B, and 2A) and the surface of the substrate 30 providedthereon with the gate insulation layer 35 and controlled in wettability(namely, the surface of the substrate 30 provided thereon with thecoating layer 37) is faced down, the nozzle 12 and the substrate 30 aremoved relative to each other (see FIGS. 2A, 2B, and 3A), whereby theorganic semiconductor material coating liquid 38A is applied to the gateinsulation layer 35. This condition is shown in the schematic partly endelevation diagram of FIG. 6B. Thereafter, the organic semiconductormaterial coating liquid 38A is dried, whereby the channel formationregion 38 composed of P3HP which is an organic semiconductor materialcan be obtained (see the schematic partly end elevation diagram in FIG.6C).

Or, in other words, in the condition where the nozzle for applying thetoluene solution of the P3HP as the coating liquid is disposed on thelower side of the substrate 30 (see FIGS. 1A, 1B, and 2A) and thesurface of the substrate 30 controlled in wettability (namely, thesurface of the substrate 30 provided thereon with the coating layer 37)is faced down, the nozzle 12 and the substrate 30 are moved relative toeach other (see FIGS. 2A, 2B, and 3A), whereby the coating liquid 38A isapplied to the desired region (specifically, the region of the gateinsulation layer 35 where the channel formation region 38 is to beformed) of the substrate 30 (see the schematic partly end elevationdiagram of FIG. 6B). Thereafter, the coating liquid 38A is dried,whereby a pattern composed of a dried coating layer, i.e., the channelformation region 38 formed of P3HP can be obtained (see the schematicpartly end elevation diagram in FIG. 6C).

[Step 220]

Thereafter, the same step as [Step 120] in Embodiment 1 is carried out,to form source/drain electrodes 36 on the channel formation regionextension portions 39. Specifically, a titanium (Ti) layer (not shown)as a close contact layer and a gold (Au) layer as the source/drainelectrodes 36 are sequentially formed on the basis of a vacuumevaporation method. In this manner, the structure as shown in FIG. 6Dcan be obtained. At the time of forming the close contact layer and thesource/drain electrodes 36, the channel formation region 38 is coveredwith a hard mask, whereby the source/drain electrodes 36 can be formedwithout any photolithographic process.

[Step 230]

Finally, the same step as [Step 140] in Embodiment 1 is carried out,whereby a bottom-gate/top-contact type organic field effect transistorcan be obtained.

Specifically, the bottom-gate/top-contact type organic field effecttransistor includes:

(a) the gate electrode 34 formed on the substrate 30,

(b) the gate insulation layer 35 formed on the gate electrode 34,

(c) the channel formation region 38 and the channel formation regionextension portions 39 which are formed on the gate insulation layer 35,and

(d) the source/drain electrodes 36 formed on the channel formationregion extension portions 39.

Embodiment 3

Embodiment 3 relates to the patterning method according to the oneembodiment of the present invention and the method of manufacturing anorganic field effect transistor according to the yet another embodimentof the present invention. Now, the patterning method in Embodiment 3 andthe method of manufacturing an organic field effect transistor inEmbodiment 3 will be described below referring to FIGS. 7A to 7D andFIGS. 8A and 8B which are schematic partly end elevation diagrams of asubstrate or the like. In Embodiment, also, the patterning method isapplied to the formation of a gate electrode and the formation of achannel formation region, in the organic field effect type transistor.

[Step 300]

First, source/drain electrodes 36 are formed on the substrate 30prepared by forming an insulation film 32 of SiO₂ on a surface of aglass substrate 31, by a lift-off method, for example. Specifically, aresist layer from which the portions to be provided with thesource/drain electrodes 36 have been removed is formed on the insulationfilm 32 on the basis of a photolithographic technique, then a titanium(Ti) layer (not shown) as a close contact layer and a gold (Au) layer asthe source/drain electrodes 36 are sequentially formed on the basis of avacuum evaporation method, and thereafter the resist layer is removed.In this manner, the structure shown in FIG. 7A can be obtained.

[Step 310]

Next, a channel formation region 38 is formed on a portion, between thesource/drain electrode 36 and the source/drain electrode 36, of thesubstrate 30 (more specifically, the insulation film 32).

For this purpose, first, a coating layer 33 composed ofoctadecyltrimethoxysilane (OTS) from which the portion to be providedwith the channel formation portion 38 has been removed is formed by aPDMS stamp method, for example. This condition is shown in the schematicpartly end elevation diagram in FIG. 7B.

Then, in the condition where a nozzle 12 for applying an organicsemiconductor material coating liquid composed of a toluene solution ofP3HP (5 g/l) is disposed on the lower side of the substrate 30 (seeFIGS. 1A, 1B, and 2A) and the surface of the substrate 30 providedthereon with the source/drain electrodes 36 and controlled inwettability (namely, the surface of the substrate 30 provided thereonwith the coating layer 33) is faced down, the nozzle 12 and thesubstrate 30 are moved relative to each other (see FIGS. 2A, 2B, and3A), whereby the organic semiconductor material coating liquid 38A isapplied to the portion, between the source/drain electrode 36 and thesource/drain electrode 36, of the substrate 30. This condition is shownin the schematic partly end elevation diagram of FIG. 7C. Thereafter,the organic semiconductor material coating liquid 38A is dried, wherebythe channel formation region 38 composed of P3HP which is an organicsemiconductor material can be obtained (see the schematic partly endelevation diagram in FIG. 7D).

Or, in other words, in the condition where the nozzle 12 for applyingthe toluene solution of P3HP as the coating liquid is disposed on thelower side of the substrate 30 (see FIGS. 1A, 1B, and 2A) and thesurface of the substrate 30 controlled in wettability (namely, thesurface of the substrate 30 provided with the coating layer 33) is faceddown, the nozzle 12 and the substrate 30 are moved relative to eachother (see FIGS. 2A, 2B, and 3A), whereby the coating liquid 38A isapplied to the desired region (specifically, the region of theinsulation film 32 to be provided with the channel formation region 38)of the substrate 30 (see the schematic partly end elevation diagram inFIG. 7C). Thereafter, the coating liquid 38A is dried, whereby a patterncomposed of a dried coating layer, i.e., the channel formation region 38formed of P3HP can be obtained (see the schematic partly end elevationdiagram in FIG. 7D).

[Step 320]

Next, a gate insulation layer 35 is formed over the entire surface.Specifically, the gate insulation layer 35 of SiO₂ is formed on theentire surface (specifically, on the channel formation region 38 and thecoating layer 33) on the basis of a sputtering method (see the schematicpartly end elevation diagram in FIG. 8A).

[Step 330]

Thereafter, a gate electrode 34 is formed on the gate insulation layer35. Specifically, the same step as [Sep 100] in Embodiment 1 is carriedout. To be more specific, first, a coating layer 37 formed ofoctadecyltrimethoxysilane (OTS) from which the portion to be providedwith the gate electrode 34 has been removed is formed on the gateinsulation layer 35 by a PDMS stamp method, for example. Then, thepatterning method according to the present invention is applied.Specifically, in the condition where the nozzle 12 for applying anaqueous PEDOT/PSS solution as the coating liquid is disposed on thelower side of the substrate 30 (see FIGS. 1A, 1B, and 2A) and thesurface of the substrate 30 controlled in wettability (namely, thesurface of the substrate 30 provided with the coating layer 37) is faceddown, the nozzle 12 and the substrate 30 are moved relative to eachother (see FIGS. 2A, 2B, and 3A), whereby the coating liquid is appliedto the desired region (specifically, the region of the gate insulationlayer 35 where the gate electrode 34 is to be formed) of the substrate30. Thereafter, the coating liquid is dried, whereby a pattern composedof a dried coating layer, i.e., the gate electrode 34 formed ofPEDOT/PSS can be obtained (see the schematic partly end elevationdiagram in FIG. 8B).

[Step 340]

Finally, the same step as [Step 140] in Embodiment 1 is carried out,whereby a top-gate/bottom-contact type organic field effect transistorcan be obtained.

Specifically, the top-gate/bottom-contact type organic field effecttransistor includes:

(a) the source/drain electrodes 36 formed on the substrate 30,

(b) the channel formation region 38 formed on the portion, between thesource/drain electrodes, of the substrate 30,

(c) the gate insulation layer 35 formed on the channel formation region38, and

(d) the gate electrode 34 formed on the gate insulation layer 35.

Embodiment 4

Embodiment 4 relates to the patterning method according to the oneembodiment of the present invention and the method of manufacturing anorganic field effect transistor according to the yet further embodimentof the present invention. Now, the patterning method in Embodiment 4 andthe method of manufacturing an organic field effect transistor inEmbodiment 4 will be described below referring to FIGS. 9A to 9D andFIGS. 10A and 10B which are schematic partly end elevation diagrams of asubstrate or the like. In Embodiment 4, also, the patterning method isapplied to the formation of a gate electrode and the formation of achannel formation region, in the organic field effect transistor.

[Step 400]

First, a channel formation region 38 and channel formation regionextension portions 39 are formed on a substrate 30.

For this purpose, first, a coating layer 33 composed ofoctadecyltrimethoxysilane (OTS) from which the portion to be providedwith the channel formation region 38 has been removed is formed by aPDMS stamp method, for example. This condition is shown in the schematicpartly end elevation diagram of FIG. 9A.

Then, in the condition where a nozzle 12 for applying an organicsemiconductor material coating liquid composed of a toluene solution ofP3HP (5 g/l) is disposed on the lower side of the substrate 30 (seeFIGS. 1A, 1B, and 2A) and the surface of the substrate 30 controlled inwettability (namely, the surface of the substrate 30 provided with thecoating layer 33) is faced down, the nozzle 12 and the substrate 30 aremoved relative to each other (see FIGS. 2A, 2B, and 3A), whereby theorganic semiconductor material coating liquid 38A is applied to theportion of the substrate 30. This condition is shown in the schematicpartly end elevation diagram of FIG. 9B. Thereafter, the organicsemiconductor material coating liquid 38A is dried, whereby the channelformation region 38 and the channel formation region extension portions39 composed of P3HP which is an organic semiconductor material can beobtained (see the schematic partly end elevation diagram in FIG. 9C).

Or, in other words, in the condition where the nozzle 12 for applyingthe toluene solution of P3HP as the coating liquid is disposed on thelower side of the substrate 30 (see FIGS. 1A, 1B, and 2A) and thesurface of the substrate 30 controlled in wettability (namely, thesurface of the substrate 30 provided with the coating layer 33) is faceddown, the nozzle 12 and the substrate 30 are moved relative to eachother (see FIGS. 2A, 2B, and 3A), whereby the coating liquid 38A isapplied to the desired region (specifically, the region of theinsulation layer 32 to be provided with the channel formation region 38)of the substrate 30 (see the schematic partly end elevation diagram inFIG. 9B). Thereafter, the coating liquid 38A is dried, whereby a patterncomposed of a dried coating layer, i.e., the channel formation region 38and the channel formation region extension portions 39 which are formedof P3HP can be obtained (see the schematic partly end elevation diagramin FIG. 9C).

[Step 410]

Thereafter, source/drain electrodes 36 are formed on the channelformation region extension portions 39. Specifically, a titanium (Ti)layer (not shown) as a close contact layer and a gold (Au) layer as thesource/drain electrodes 36 are sequentially formed on the basis of avacuum evaporation method. In this manner, the structure shown in FIG.9D can be obtained. At the time of forming the source/drain electrodes36, the region where to form the channel formation region 38 is coveredwith a hard mask, whereby the source/drain electrodes 36 can be formedwithout any photolithographic process.

[Step 420]

Next, a gate insulation layer 35 is formed over the entire surface.Specifically, the gate insulation layer 35 composed of SiO₂ is formed onthe entire surface (specifically, on the channel formation region 38 andthe source/drain electrodes 36) on the basis of a sputtering method (seethe schematic partly end elevation diagram in FIG. 10A).

[Step 430]

Thereafter, the same step as [Step 330] in Embodiment 3 is carried out.Namely, a gate electrode 34 is formed on the gate insulation layer 35.For this purose, first, a coating layer 37 composed ofoctadecyltrimethoxysilane (OTS) from which the portion where to form thegate electrode 34 has been removed is formed on the gate insulationlayer 35 by a PDMS stamp method, for example. Next, the pattering methodaccording to the present invention is applied. Specifically, in thecondition where the nozzle 12 for applying an aqueous PEDOT/PSS solutionas the coating liquid is disposed on the lower side of the substrate 30(see FIGS. 1A, 1B, and 2A) and the surface of the substrate 30controlled in wettability (namely, the surface of the substrate 30provided with the coating layer 37) is faced down, the nozzle 12 and thesubstrate 30 are moved relative to each other (see FIGS. 2A, 2B, and3A), whereby the coating liquid is applied to the desired region(specifically, the region of the gate insulation layer 35 to be providedwith the gate electrode 34) of the substrate 30. Thereafter, the coatingliquid is dried, whereby a pattern composed of a dried coating layer,i.e., the gate electrode 34 formed of PEDOT/PSS can be obtained (see theschematic partly end elevation diagram in FIG. 10B).

[Step 440]

Finally, the same step as [Step 140] in Embodiment 1 is carried out,whereby a top-gate/top-contact type organic field effect transistor canbe obtained.

Specifically, the top-gate/top-contact type organic field effecttransistor includes:

(a) the channel formation region 38 and the channel formation regionextension portions 39 which are formed on the substrate 30,

(b) the source/drain electrodes 36 formed on the channel formationregion extension portions 39,

(c) the gate insulation layer 35 formed on the source/drain electrodes36 and the channel formation region 38, and

(d) the gate electrode 34 formed on the gate insulation layer 35.

Embodiment 5

Embodiment 5 relates to the patterning method according to the oneembodiment of the present invention. In Embodiment 5, a substrate 30 isprovided with a recess-projection structure having a recessed portion asa desired region and a projected portion, whereby the wettability of thesurface of the substrate 30 is controlled. Then, a coating liquid isapplied to the recessed portion. Further, after a pattern composed of adried coating layer is formed, the pattern is transferred onto a secondsubstrate.

Specifically, as a schematic partly end elevation diagram is shown inFIG. 11A, the substrate 30 composed of a glass substrate 41 is providedwith a recess-projection structure having a recessed portion 42 as adesired region and a projected portion 43. Incidentally, the projectedportion 43 is formed of perfluorooctyltrichlorosilane in a thickness ofseveral nanometers, and can be formed by a lift-off method, for example.

In this condition, the patterning method according to the presentinvention is carried out. Specifically, in the condition where a nozzle12 for applying a toluene solution of P3HP as a coating liquid isdisposed on the lower side of the substrate 30 (see FIGS. 1A, 1B, and2A) and the surface of the substrate controlled in wettability (namely,the surface of the substrate 30 provided with the recess-projectionstructure) is faced down, the nozzle 12 and the substrate 30 are movedrelative to each other (see FIGS. 2A, 2B, and 3A), whereby the coatingliquid 44A is applied to the desired region (specifically, the recessedportion 42) of the substrate 30 (see the schematic partly end elevationdiagram in FIG. 11B). Thereafter, the coating liquid 44A is dried,whereby a pattern 44 composed of a dried coating layer, i.e., a layerconstituting the channel formation region composed of P3HP, for example,can be obtained.

Thereafter, a layer constituting the channel formation region which isthe pattern may be transferred, for example, to a second substrate inthe state shown in FIG. 5A, a second substrate in the state shown inFIG. 6A (it should be noted that it is unnecessary to form the coatinglayer 37), a second substrate in the state shown in FIG. 7A, or a secondsubstrate in the state shown in FIG. 9A (it should be noted that it isunnecessary to form the coating layer 33), to thereby forming thechannel formation region 38 as the desired pattern on the secondsubstrate.

Or, alternatively, a method may be adopted wherein the coating liquid44A is applied to the desired region (specifically, the recessed portion42) of the substrate 30, and then the coating liquid 44A is dried,whereby a pattern 44 composed of a dried coating layer, i.e., a layerconstituting a gate electrode composed of PEDOT/PSS, for example, can beobtained. Thereafter, the layer constituting the gate electrode as thepattern may be transferred, for example, to a second substrate in thestate shown in FIG. 4A (it should be noted that it is unnecessary toform the coating layer 33) or to a second substrate in the state shownin FIG. 8A, to thereby form the gate electrode 34 as the desired patternon the second substrate.

Or, a method may be adopted wherein the coating liquid 44A is applied tothe desired region (specifically, the recessed portion 42) of thesubstrate 30, and then the coating liquid 44A is dried, whereby apattern 44 composed of a dried coating layer, i.e., a layer constitutingsource/drain electrodes composed of PEDOT/PSS, for example, can beobtained. Thereafter, the layer constituting the source/drain electrodesas the pattern may be transferred, for example, to a second substrate inthe state shown in FIG. 4D, a second substrate in the state before theformation of the source/drain electrodes 36 shown in FIG. 7A, or asecond substrate in the state shown in FIG. 9C, to thereby form thesource/drain electrodes 36 as the desired pattern on the secondsubstrate.

Specific examples of the method for transferring the pattern onto thesecond substrate include a method in which, for example,poly-3-hexylthiophene (P3HP) as an ink is mounted on a projected portionof a stamp having a recess-projection structure (a stamp formed from afluoro-resin, a stamp formed from a substrate surface-treated with afluoro-resin, or s stamp treated with 10 mmol OTS), thereafter the P3HPmounted on the projected surface of the stamp is transferred onto a PDMS(silicone rubber) flat over the entire surface, then the P3HPtransferred onto the PDMS is transferred onto the second substrate.

Embodiment 6

Embodiment 6 is a modification of Embodiment 5. Now, the patterningmethod in Embodiment 6 will be described below referring to FIGS. 12A to12D which are schematic partly sectional diagrams of a substrate or thelike.

In Embodiment 6, first, a resist layer 52 is formed on the surface of asubstrate 30 composed of a glass substrate 51, based on the knownphotolithographic technique (see FIG. 12A).

Next, the whole body of the substrate is dipped in a metaxylenehexafluoride solution of perfluorooctyltrichlorosilane which is aliquid-repellent surfactant (contact angle θ′=about 120° when in contactwith the glass substrate 51), or is exposed to the vapor of thissolution, whereby the portion of the substrate 30 not covered with theresist layer 52 is treated to be water-repellent (see FIG. 12B).

Subsequently, after the removal of the resist layer 52, the whole bodyof the substrate is dipped in an anhydrous ethanol solution ofaminotrichlorosilane which is a lyophilic surfactant (contact angleθ=not more than about 30° when in contact with the glass substrate 51),whereby the portion of the substrate 30 having been covered with theresist layer 52 is treated to be hydrophilic (see FIG. 12C).Incidentally, aminotrichlorosilane would not adhere to thewater-repellent treated surface.

In this condition, the patterning method according to the one embodimentof the present invention is carried out. Specifically, in the conditionwhere a nozzle 12 for applying an aqueous solution of PEDOT/PSS which isthe coating liquid is disposed on he lower side of the substrate 30 (seeFIGS. 1A, 1B, and 2A) and the surface of the substrate 30 controlled inwettability (namely, the surface of the substrate 30 having thehydrophilic treated surface and the water-repellent treated surface) isfaced down, the nozzle 12 and the substrate 30 are moved relative toeach other (see FIGS. 2A, 2B, and 3A), whereby the coating liquid 54A isapplied to the desired region (specifically, the hydrophilic treatedsurface) of the substrate 30 (see the schematic partly end elevationdiagram in FIG. 12D). Thereafter, the coating liquid 54A is dried,whereby a pattern 54 composed of a dried coating layer can be obtained.Thereafter, it suffices that the pattern is transferred onto a secondsubstrate by the same method as described in Embodiment 5.

Embodiment 7

Embodiment 7 relates to the method of manufacturing a flexible printedcircuit board according to the still another embodiment of the presentinvention.

In the method of manufacturing a flexible printed circuit board inEmbodiment 7, first, a surface of a substrate 30 composed of a PES filmwith a thickness of 100 μm, for example, is subjected to an oxygenplasma treatment, whereby the surface of the substrate 30 becomes ahydrophilic treated surface. Next, toner particles are transferred andfixed onto the surface of the substrate 30 by use of a dry indirectelectrostatic copying machine, whereby a liquid-repellent regioncomposed of the toner particles and patterned is formed on the surfaceof the substrate 30. Incidentally, since the substrate 30 is flexible,the above operations can be conducted on a roll form substrate 30 on theso-called roll-to-roll basis.

Next, in the condition where a nozzle 12 for applying a conductivematerial coating liquid composed of an aqueous PEDOT/PSS solution, forexample, is disposed on the lower side of the substrate 30 (see FIGS.1A, 1B, and 2A) and the surface of the substrate controlled inwettability (the surface of the substrate 30 which is provided thereonwith the liquid-repellent region composed of the toner particles andpatterned, the other region being the hydrophilic treated surface) isfaced down, the nozzle 12 and the substrate 30 are moved relative toeach other (see FIGS. 2A, 2B, and 3A), whereby the conductive materialcoating liquid is applied to the substrate 30, and then the conductivematerial coating liquid is dried, whereby a circuit pattern (flexibleprinted circuit board) composed of the dried conductive material coatinglayer (specifically, a PEDOT/PSS layer) can be obtained. Incidentally,in some cases, the circuit pattern thus obtained may be transferred ontoa second substrate.

While the present invention has been described above based on thepreferred embodiments thereof, the invention is not limited to or by theembodiments. The structures or configurations, manufacturing conditions,and the manufacturing methods of the organic field effect transistorsand the flexible printed circuit board as above-described are mereexamples, and can therefore be modified appropriately. In the case wherethe organic field effect transistors (TFTs) obtained according to thepresent invention are applied to or used in displays or variouselectronic apparatuses, a multiplicity of the TFTs may be integrated ona support body or support member to obtain a monolithic integratedcircuit, or the respective TFTs may be cut off individually to be useddiscrete component parts. In addition, the patterning method accordingto the one embodiment of the present invention is applicable, forexample, to the manufacture of organic electroluminescence displays,organic solar cells, various sensors, and color filters.

1. A patterning method wherein a nozzle for applying a coating liquidand a substrate are moved relative to each other where said nozzle isdisposed on a lower side of said substrate and a substrate surfacecontrolled in wettability is faced down, so as thereby to apply saidcoating liquid to a desired region of said substrate, and thereaftersaid coating liquid is dried so as thereby to obtain a pattern includinga dried coating layer.
 2. The patterning method as set forth in claim 1,wherein said substrate is provided with a recess-projection structurehaving a recessed portion as said desired region and a projected portionso as thereby to control the wettability of the surface of saidsubstrate, and said coating liquid is applied to said recessed portion.3. The patterning method as set forth in claim 1, wherein therelationship of θ<θ′ is satisfied, where θ is a contact angle betweensaid desired region of said substrate and said coating liquid, and θ′ isa contact angle between a region of said substrate other than saiddesired region and said coating liquid.
 4. The patterning method as setforth in claim 1, wherein after said pattern including said driedcoating layer is obtained, said pattern is transferred onto a secondsubstrate.
 5. A method of manufacturing an organic field effecttransistor, comprising the steps of: (A) forming a gate electrode on asubstrate, (B) thereafter forming a gate insulation layer over an entiresurface, (C) then forming source/drain electrodes on said gateinsulation layer, and (D) thereafter forming a channel formation regionin a portion, between said electrodes, of said gate insulation layer,wherein in said step (D), a nozzle for applying an organic semiconductormaterial coating liquid and said substrate are moved relative to eachother where said nozzle is disposed on a lower side of said substrate,and a substrate surface provided thereon with said gate insulation layerand said source/drain electrodes and controlled in wettability is faceddown, so as thereby to apply said organic semiconductor material coatingliquid to the portion, between said electrodes, of said gate insulationlayer, and thereafter said organic semiconductor material coating liquidis dried so as thereby to obtain a channel formation region includingthe organic semiconductor material.
 6. A method of manufacturing anorganic field effect transistor, comprising the steps of: (A) forming agate electrode on a substrate, (B) thereafter forming a gate insulationlayer on an entire surface, (C) then forming a channel formation regionand channel formation region extension portions on said gate insulationlayer, and (D) thereafter forming source/drain electrodes on saidchannel formation region extension portions, wherein in said step (C), anozzle for applying an organic semiconductor material coating liquid andsaid substrate are moved relative to each other where said nozzle isdisposed on a lower side of said substrate and a substrate surfaceprovided thereon with said gate insulation layer and controlled inwettability is faced down, so as thereby to apply said organicsemiconductor material coating liquid to said gate insulation layer, andthereafter said organic semiconductor material coating liquid is driedso as thereby to obtain said channel formation region and said channelformation region extension portions on which is included an organicsemiconductor material.
 7. A method of manufacturing an organic fieldeffect transistor, comprising the steps of: (A) forming source/drainelectrodes on a substrate, (B) thereafter forming a channel formationregion in a portion, between said electrodes, of said substrate, (C)then forming a gate insulation layer on an entire surface, and (D)thereafter forming a gate electrode on said gate insulation layer,wherein in said step (B), a nozzle for applying an organic semiconductormaterial coating liquid and said substrate are moved relative to eachother where a substrate surface provided thereon with said source/drainelectrodes and controlled in wettability is faced down, so as thereby toapply said organic semiconductor material coating liquid to a portion,between said electrodes, of said substrate, and thereafter said organicsemiconductor material coating liquid is dried so as thereby to obtainsaid channel formation region including an organic semiconductormaterial.
 8. A method of manufacturing an organic field effecttransistor, comprising the steps of: (A) forming a channel formationregion and channel formation region extension portions on a substrate,(B) thereafter forming source/drain electrodes on said channel formationregion extension portions, (C) then forming a gate insulation layer overan entire surface, and (D) thereafter forming a gate electrode on saidgate insulation layer, wherein in said step (A), a nozzle for applyingan organic semiconductor material coating liquid and said substrate aremoved relative to each other where said nozzle is disposed on a lowerside of said substrate and a substrate surface controlled in wettabilityis faced down, so as thereby to apply said organic semiconductormaterial coating liquid to said substrate, and thereafter said organicsemiconductor material coating liquid is dried so as thereby to obtainsaid channel formation region and said channel formation regionextension portions on which is included an organic semiconductormaterial.
 9. A method of manufacturing a flexible printed circuit board,wherein a nozzle for applying a conductive material coating liquid and asubstrate are moved relative to each other where said nozzle is disposedon a lower side of said substrate and a substrate surface controlled inwettability is faced down, so as thereby to apply said conductivematerial coating liquid to said substrate, and thereafter saidconductive material coating liquid is dried so as thereby to obtain acircuit pattern including a conductive material coating layer.